Norway's fishery minister has stepped down after harsh criticism for not informing the government of his private trips abroad to Iran and China.

Per Sandberg, 58, gave no reasons why he failed to tell his bosses about the trips in advance — a summer holiday in July to Iran with his Iranian-born girlfriend and a trip to China in May. In Norway, government members are required to report before going to another country on private trips.

After returning from Iran, his work phone was given to Norway's domestic intelligence service to make sure it was not hacked. The PST agency considers Iran "a high risk country" when it comes to electronic surveillance.

He was replaced in the fisheries post Monday by Harald Tom Nesvik.

The trip risked exposing Sandberg to Iranian spies, as he should not have taken a work phone with him.

Letnes is a former beauty queen who now manages a fish export business. She has Norwegian residency and has denied any links to Iran's Islamist government. Norwegian intelligence is reported to be investigating her activities now.

Prime Minister Erna Solberg said she had ordered Mr Sandberg to hand his phone to police for safety checks. He has also resigned as deputy leader of the Progress Party.

"Per himself asked to step down, and I think it was the right decision," Ms Solberg, a Conservative, told reporters.

"He didn't show the necessary common sense when it comes to handling security issues," AFP news agency quoted her as saying.